The mission of the MBL Physiology Course is to provide interdisciplinary training in cell physiology: training that both anticipates and drives th evolution of modern biomedical research. Because living cells are complex systems, a key challenge for the future of cell physiology is to integrate advanced experimental techniques with quantitative analysis and computational modeling. To meet this challenge, the Physiology Course provides a unique, interdisciplinary training environment and research program. We bring together biological and physical/computational scientists, both as faculty members and students to work together on unanswered questions at the cutting edge of biomedical research. The course emphasizes traditional topics in cell biology -including cell motility, cell division, ad signaling -as well as the need to attack these problems at multiple size scales, using: single-molecule techniques; in vitro reconstitutions; high-resolution cell imaging; and studies of cell-cel interaction. The heart of the course is a set of three, 2-week research sessions that emphasize learning by practice and promote experimental creativity and interdisciplinary approaches. Experimental work is accompanied by computational analysis and theory to provide a deeper understanding of both the biological systems being studied and the modern practice of biomedical research. The co-directors of the course, Dyche Mullins and Clare Waterman are leading cell biologists with strong training records and complementary skills. Dyche's background is in engineering and mathematics but he has worked hard to become a bona fide cell biologist. Clare began as a cell biologist but her current work relies heavily on quantitative and computational approaches and is influenced by soft condensed matter physics. Both are alumni of the 1993 Physiology Course and both served for years as faculty members in the course before taking it over. They have assembled an outstanding faculty, with backgrounds in cellular physiology, physics, engineering and computational science. In addition, the co-directors have recruited a set of distinguished visiting scholars and members of the MBL scientific community to provide additional training. We strive to make this course a widely recognized venue for interdisciplinary training, one where experimental, computational, and theoretical scientists gather to share their philosophies and approaches. We request continued support for this exciting endeavor. The current application is for a competitive renewal of an award originally funded under the NIH Roadmap Initiative and then renewed under the R13 mechanism.